Interface for digital telecommunications system

ABSTRACT

A node ( 2 ) and a local exchange ( 1 ) communicate with each other over a V5.2 interface created in response to instructions prepared by a computer ( 22 ). The method of preparing the instructions involves the steps of allocating identification data to the signal means linking the node and the local exchange so as to enable the latter to determine the identity of the node communicating over the signal link, specifying which C channels are to be transmitted along the signal link means, and, for each specified channel, specifying the C paths, i.e. the type of telecommunications traffic, to be carried thereby.

This application claims the benefit of the earlier filed InternationalApplication No. PCT/GB99/03976. International Filing Date, Nov. 30,1999, which designated the United States of America, and whichinternational application was published under PCT Article 21(2) inEnglish as WO Publication No. WO 00/40055.

FIELD OF THE INVENTION

This invention relates to a method of creating an interface between anode and a local exchange of a digital telecommunications system, and toapparatus for preparing instructions for the creation of such aninterface. The invention is particularly applicable to the creation of aV5.2 interface between an Access Node (AN) and a local exchange of anSDH telecommunications system.

BACKGROUND TO THE INVENTION

The node of a telecommunications system is programmed with node managersoftware which enables the node to be configured and maintained. Duringthe installation of the node, that software is also used to create aninterface between the node and its local exchange of thetelecommunications system in response to a set of instructions whichwill include various parameters input by an engineer installing theinterface.

In general, the manager software will be able to warn the engineer ifany of the parameters have been incorrectly set. However, correcting theparameters can be a time-consuming and confusing process since some ofthe parameters are interrelated such that the correction of oneparameter can have a bearing on the requirements of the otherparameters.

SUMMARY OF THE INVENTION

According to the invention, there is provided a method of creating aninterface between a node and a local exchange of a digitaltelecommunications system to enable a number of different types oftelecommunications traffic to pass along a plurality of channels fromone to the other of the node and the local exchange over signal linkmeans, the method comprising performing, in sequence, the steps of:

(a) allocating identification data to the signal means to enable thelocal exchange to determine the identity of the node;

(b) specifying which of the channels are to be transmitted along thesignal link means; and

(c) for each specified channel, specifying the type oftelecommunications traffic to be carried thereby.

This particular sequence of steps facilitates the creation of aninterface since any important errors in or omissions from theinformation provided at each step can be rectified before the subsequentsteps occur and without affecting the information (if any) provided forthe previous steps.

The steps of the method can be performed by inputting appropriate datainto a suitable data processing device, for example a lap top computer,which then transmits the data to the node as a set of instructions forthe latter to set up the interface.

Preferably, the steps of the method constitute the preparation ofinstructions for the setting up of the interface, the method comprisingthe further step of subsequently implementing the instructions. It willbe appreciated that the sequence of steps involved in the implementationof the instructions need not necessarily be the same as the sequence ofsteps involved in preparing the instructions.

Preferably, the signal link means comprises a plurality of data links,for example cables, physically connecting the node to the localexchange. In this case, a respective identification is preferablyallocated to each link.

Preferably, the interface allows various overhead signals for thetelecommunications traffic to pass from one to the other of the node andlocal exchange.

The telecommunications traffic can be arranged in a succession of frameshaving time slots for channels for the overhead signals, in which casesteps (b) and (c) are preferably performed by specifying along whichlink each of those channels is to be conveyed, and for each channel, thenature of the overhead signal to be carried thereby.

Preferably, step (c) also involves specifying which of said channels isto carry vital signals for maintaining said interface. The methodpreferably also includes the step of checking whether a channel for saidsignals has been allocated, and preventing the implementation of theinstructions until such an allocation has been made. Thus, the risk ofsetting up an interface with no channel for vital control signals isavoided.

The method preferably includes the further step of ensuring that, beforethe instructions are implemented, a back up channel, for carrying thevital control signals in the event of the failure of the first saidchannel for those signals has been allocated.

The local exchange may be connected to each of a plurality of nodes viaa respective interface created by this method, the method thereforeincluding the additional step of allocating a respective identificationto the interface.

Preferably, that additional step is the first step of the method.

Preferably, the interface is a V5.2 interface.

The invention also lies in data processing apparatus for preparinginstructions for the creation of an interface bet ween a node and thelocal exchange of a digital telecommunications system, the apparatuscomprising data input means for enabling the apparatus to receive thedata necessary to prepare the instructions, and signal output means forsupplying a signal, which contains said instructions, to the system,wherein the apparatus is so arranged as to require the following datafor the instructions to be input into the apparatus in the followingsequence:

a) data identifying signal link means via which the node and localexchange are to communicate with each other;

b) data specifying the communications channels to be transmitted overthe signal link means; and

c) for each such channel, data specifying the type of telecommunicationstraffic to be carried thereby.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only, withreference to the accompanying drawings in which:

FIG. 1 is a schematic block diagram showing a local exchange and anumber of nodes of an SDH telecommunications system, each nodecommunicating with the local exchange over a V5.2 interface created by amethod in accordance with the invention;

FIGS. 2 to 5 are sample displays generated by a PC for prompting anoperator to input data on various parameters for each interface; and

FIG. 6 is also a sample display, this time providing a summary of theinformation which has been input into the computer.

DETAILED DESCRIPTION

With reference to FIG. 1, a local exchange 1 of an SDHtelecommunications system is connected to each of the nodes 2, 4, 6, 8and 10. The nodes are physically connected to the local exchange 1through corresponding bundles of optical fibres 12, 14, 16, 18 and 20.Each fibre provides a 2 Mb/s signal link between the node to which it isconnected and the local exchange.

The nodes shown in FIG. 1 are identical, and only the node 2 willtherefore be described. That node is known as an Access Node (AN), andcontains various different units, for example, a Node Control Unit, typeA, a number of Public Switched Telephone Network (PSTN) units and anumber of Integrated Services Digital Network (ISDN) units. The node isprogrammed with management software for managing various functions ofthe node, including the setting up of a V5.2 interface with the localexchange 1. That software can be accessed through a lap top computer 22connected to the node 2.

Software in the lap top computer 22 includes a Create Wizard applicationfor creating a V5.2 interface between the node 2 and the local exchange1. If a user instructs the lap top computer to open the Create Wizardapplication, the PC checks whether a V5.2 interface has already beencreated between the node 2 and local exchange 1, and if not opens theapplication. If, however, a V5.2 interface already exists, the PCinforms the operator of this and/or opens another application (such asfor reconfiguring the interface).

When opened, the Create Wizard initially causes the display of the PC todisplay the window shown in FIG. 2.

Each of the V5.2 interfaces is identified by a respective code, and thewindows shown in Figure invites the user to input a suitableidentification code at box 24. In this case, the code identifies theinterface to be formed between the node 2 and local exchange 1. Codesfor all the possible V5.2 interfaces between the local exchange 1 andthe nodes may already have been supplied to the local exchange 1, inwhich case the code entered at box 24 will have to be selected by theuser from one of the existing codes which has not already been allocatedto an interface already created with another node.

Once the code has been entered into the lap top computer 22, the windowshown in FIG. 3 is presented to prompt the user to specify which of thefibre optic cables (in this case the cables in the bundle 12), isconnected to which port of the node 2. This enables the local exchange 1to identify which node is connected via those 2 Mb/s links.

The window shown in FIG. 3 includes a table, the left hand column ofwhich indicates a slot (i.e. a card) in the node, and an interface forthe fibre optic cables connected to the slot. In the present example,there is one slot, designated U1, having connections for four fibreoptic cables through interfaces i/f 1-4. The operator inputs numbersidentifying the relevant optical fibres (in this case 4 and 3) in thecolumn headed ID, to indicate which fibre is connected to the slot U1through which interface. The table also includes the column headed“block source” which enables the user to prevent traffic from travellingalong a specified fibre. Blocking or unblocking a fibre has to be donewhen the V5.2 interface is not operating, which in this case isinevitable as the V5.2 interface has yet to be created.

The identity code for the fibres enables the local exchange to identifywhich cable is connected to which node.

The table has a number of other columns which are concerned with thealtering of a V5.2 interface, but these are not relevant to the processof creating the interface. Various other option buttons in the table areself-explanatory.

Once the identities of the 2 Mb/s links have been entered, the CreateWizard on the PC displays the window shown in FIG. 4. This window alsohas a table, which incorporates the information on the link location andidentities of optical fibres entered in the previous window. Inaddition, the table includes columns which represent the time Blots foroverhead signals between the node 2 and the local exchange 1. Inaccordance with relevant standards, those time slots are time slots 15,16 and 31.

The portion of the table which is not shaded contains boxes in which theuser can enter the identifications of the C channels to be carried onthe time slots and fibres represented in the table. Thus, in the presentcase, channel No. 123 is to be carried on fibre No. 4 and via time slot15, whilst time slot 16 is to carry channel No. 456 on the same fibre.Time slot 16 on fibre No. 3 is to provide a “vital” standby channel foruse if the channel which is to carry the control signals for the V5.2interface fails. A further standby channel is reserved on time slot 31on the same fibre, and this can be used if a channel for other overheadsignals fails.

The next window to be presented is shown in FIG. 5, and it includes atable corresponding to the table shown in FIG. 4. In this case, the userhas to specify the C-paths, i.e. the type of control signals to beconveyed on the available channels. Thus, channel No. 123 is used toconvey PSTN and ISDN control signals, whilst channel No. 456 is to carrythe control signals for that V5.2 interface.

The next window to be displayed on the Lap top computer is shown in FIG.6, and just provides a summary of the data entered at the previoussteps. The window includes a create button for causing the Lap topcomputer to pass the data to the management software in the node 2 toimplement the instructions to create the V5.2 interface on the basis ofthe data supplied by the user.

Although the described system is set up to provide only one V5.2interface for the node, the method according to the invention can beused to set up a plurality of V5.2 interfaces between the node and alocal exchange (where the system permits).

What is claimed is:
 1. A method of creating an interface between a nodeand a local exchange of a digital telecommunications system to enable anumber of different types of telecommunications traffic to pass along aplurality of channels from one to the other of the node and the localexchange over signal link means, the method comprising performing, insequence, the steps of: (a) allocating identification data to the signallink means to enable the local exchange to determine the identity of thenode; (b) specifying which of the channels are to be transmitted alongthe signal link means; and (c) for each specified channel, specifyingthe type of telecommunications traffic to be carried thereby.
 2. Amethod according to claim 1, in which steps (a)-(c) are performed byinputting appropriate data into a suitable data processing device, whichthen transmits the data to the node as a set of instructions for thelatter to set up the interface.
 3. A method according to claim 2, inwhich instructions for the setting up of the interface are prepared byperforming steps (a)-(c), the method comprising the further step ofsubsequently implementing the instructions.
 4. A method according toclaim 1, in which the signal link means comprises a plurality of linksphysically connecting the node to the local exchange, and in which arespective identification is allocated to each link.
 5. A methodaccording to claim 4, in which the interface is to allow variousoverhead signals for the telecommunications traffic to pass from one tothe other of the node and local exchange, the telecommunications trafficbeing arranged in a succession of frames having time slots for channelsfor the overhead signals, and steps (b) and (c) being performed byspecifying along which link each of those channels is to be conveyed,and for each channel, the nature of the overhead signal to be carriedthereby.
 6. A method according to claim 5, in which step (c) alsoinvolves specifying which of said channels is to carry vital signals formaintaining said interface.
 7. A method according to claim 6, in whichthe method preferably also includes the step of checking whether achannel for said signals has been allocated, and preventing theimplementation of the instructions until such an allocation has beenmade.
 8. A method according to claim 7, in which the method includes thefurther step of ensuring that, before the instructions are implemented,a back up channel, for carrying the vital signals in the event of thefailure of the first said channel for those signals has been allocated.9. A method according to claim 1, in which the local exchange isconnected to each of a plurality of nodes via a respective interface socreated, the method including the additional step of allocating arespective identification to the interface.
 10. A method according toclaim 9, in which the additional step of allocating an identification tothe interface is the first step of the method.
 11. A method according toclaim 1, in which the interface is a V5.2 interface.
 12. Data processingapparatus for preparing instructions for the creation of an interfacebetween a node and the local exchange of a digital telecommunicationssystem, the apparatus comprising: data input means for enabling theapparatus to receive the data necessary to prepare the instructions; andsignal output means for supplying a signal, which contains saidinstructions, to the system, wherein the apparatus is so arranged as torequire the following data for the instructions to be input into theapparatus in the following sequence: a) data identifying signal linkmeans via which the node and local exchange are to communicate with eachother; b) data specifying the communications channels to be transmittedover the signal link means; and c) for each such channel, dataspecifying the type of telecommunications traffic to be carried thereby.